Town Square

Could it happen here?

Original post made
on Mar 17, 2011

The massive 9.0 magnitude earthquake and ensuing tsunami that rocked Japan last week has people all over the Bay Area and California thinking about the next big one. Though experts from the United States Geological Survey said that residents of inland, bay-bordering cities such as Mountain View aren't at risk from a tsunami, the prospect of a major earthquake is very real.

1989 earthquake in San Francisco was of magnitude 6.9 on Richter Scale. Japan's earthquake was of magnitude 8.9 (now upgraded to 9.0). Per Web Link. "For each whole number increase, the amount of energy is 31 times greater than the preceding whole number. Using the same Richter scale measurement, a 6.3 releases 31 times more energy than a 5.3 but 961 times more energy is released as compared to a 4.3."

That would make Japan's earthquake 961++ times the intensity of the 1989 earthquake here. Despite all the earthquake preparedness in Japan, most of its earthquake zone structures were washed off or damaged irreparably and tens of thousands of people are believed killed. Over $100 billion in damage.

What should be the strategy for personal safety and to prevent destruction of our homes? There are earthquake standards for homes, which should be made tougher. In addition, I feel in each home there should be a small helmet, hiker's backpack with bedding, emergency food rations, water, medications for each person. These should be placed strategically near the front door. In case of an earthquake, I have read - hide under furniture, get out of the house to open space (take the helmet, pre-packed hiker's backpack). Of course surviving a Tsunami would require a different defense. All this should be thought about. Personally, I think survival in a 9.0 earthquake is a matter of luck - no amount of preparedness will be foolproof.

Posted by Steve
a resident of Shoreline West
on Mar 17, 2011 at 3:36 pm

vkmo- thanks for the addition of useful information in your comment. Indeed, there is "no amount of preparedness" that will be foolproof under these circumstances. However, architecturally there are buildings such as geodesic domes and pyramidal structures that can provide considerable resilience to such earthquakes.

With regard to "tidal waves" (a more descriptive term), I think it may be a mistake to disregard the possible occurrence of a large "tidal wave" hitting the coast of California. However remote the possibility, a "tidal wave" could align in just the right way, such that it enters through the Golden Gate and wraps around the bay area; a small one from last week went right up both the Santa Cruz boat harbor and San Lorenzo River.

A "tidal wave" is not the same thing as a tsunami. The tidal wave is literally the result of a large tide, and does not have the ripple-like propagation of a tsunami, nor the maximum power that a tsunami can have, since it doesn't result from as violent a force. Tsunamis used to be called tidal waves, but apparently they have been clearly distinguished enough that nobody uses tidal wave anymore.

A tsunami entering the bay is heavily dissipated because of the relatively small opening into a much larger body of water. While the exact amount of dissipation is hard to predict, in the 9.4 earthquake in Alaska in 1964, the wave height at Richmond and Hunters' point was about half that at the Golden Gate, and at Alviso it was 1/10th that at the GG.

Posted by Sue Nahmi
a resident of Cuesta Park
on Mar 18, 2011 at 2:41 pm

The type of quakes Japan has are caused by one plate shoving under another(called a subduction fault). Our quakes are caused by plates slipping alongside one another.
We can get some good ones with our slip faults, but a subduction fault is capable of much stronger quakes, like the latest in Japan.

Posted by steven Nelson
a resident of Cuesta Park
on Mar 25, 2011 at 10:37 am

The City of Mountain View, through its cooperative agreement with the local school district, built a very nice emergency water storage facility + well + diesel pump station at Graham Middle School's field. The nice thing about such a facility- our piped-in water supply would be cut in a large earthquake - and this facility could operate without electric power to supply drinking water for months.
-keep your buckets ready-

Posted by Steve
a resident of Shoreline West
on Apr 1, 2011 at 3:31 pm

Architecturally there are buildings such as geodesic domes and pyramidal structures that can provide considerable resilience to such earthquakes. Better than geodesic domes are geodesic spheres such that half of the sphere is above ground and the other below. Such a structure could allow for a "basement" like level or other green ecologically sustainable technologies for processing waste etc. Above ground a good portion of the could be devoted to solar-cells for the transduction of sunlight into electricity. Also, such structures are resilient in earthquakes and potentially so in hurricanes and floods.